ER_AtomicNucleus

An atom is made of three sub-atomic particles: protons, neutrons, and electrons. The protons and neutrons are found in a nucleus at the center of the atom. The protons and neutrons have roughly the same weight, and they make up virtually all of the mass of the atom—the electron is barely noticeable. When atoms combine to form different molecules (a chemical change), the electrons clouds interact, but the nuclei remain separate.
In a nuclear change, the nucleus itself changes. For many years, scientists assumed that nuclear changes were not possible. For this assignment, we will use this old assumption as we learn what is inside the nucleus of the atom.
You can find some information on the Periodic Table of the Elements. As you fill in the following table, remember:

• the “Atomic Number” is the same as the “Number of Protons”;
• the “Mass Number” is the same as the “Number of Protons” + “Number of Neutrons”;
• the “Isotope Name” is the “Symbol” followed by the “Mass Number”.

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